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<head>
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    <title>Document</title>
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</head>

<body>
    <button type="button" class="btn btn-primary" data-toggle="modal" data-target="#myModal">
        Launch demo modal
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    <button type="button" class="btn btn-primary" data-toggle="modal" data-target="#myModal">
        打开模态框
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    <!-- Modal -->
    <div class="modal fade " id="exampleModalCenter" tabindex="-1 " role="dialog " aria-labelledby="exampleModalCenterTitle " aria-hidden="true ">
        <div class="modal-dialog modal-dialog-centered " role="document ">
            <div class="modal-content ">
                <div class="modal-header ">
                    <h5 class="modal-title " id="exampleModalCenterTitle ">Modal title</h5>
                    <button type="button " class="close " data-dismiss="modal " aria-label="Close ">
            <span aria-hidden="true ">&times;</span>
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                <div class="modal-body ">
                    ...
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                <div class="modal-footer ">
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                    <button type="button " class="btn btn-primary ">Save changes</button>
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    <div class="modal fade" id="myModal">
        <div class="modal-dialog">
            <div class="modal-content">

                <!-- 模态框头部 -->
                <div class="modal-header">
                    <h4 class="modal-title">模态框头部</h4>
                    <button type="button" class="close" data-dismiss="modal">&times;</button>
                </div>

                <!-- 模态框主体 -->
                <div class="modal-body">
                    模态框内容..
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                <!-- 模态框底部 -->
                <div class="modal-footer">
                    <button type="button" class="btn btn-secondary" data-dismiss="modal">关闭</button>
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